FILEZILLA sent "CLNT FileZilla" command to FTP serveurs when Generic proxy is used which breaks connections

[tpr-0405]

Dear support,

I am using the last filezilla version 3.30 64bits and I wanted to inform you about this strange behavior :
When a generic proxy is used and configured in Filezilla (FTP connection is send through HTTP CONNECT), after BASIC authentication on the proxy and logon on the remote FTP server, the Filezilla client send the following command :

"Request: CLNT FileZilla"

Most of the remote FTP server breaks the connection when this command is sent.
Without a proxy configured, Filezilla don't send this command and the connection work fine.
Other client like "Total Commander" don't send this CLNT command, so we need currently to use this tool to connect to FTP servers through our proxies.
Whould it be not better to remove the sending of command "Request: CLNT FileZilla" when generic HTTP proxy is used ?

Thanks a lot,

Regards,

[tpr-0405]

Capture with the request CLNT Filezilla which cause the connection closure by the FTP server

[Tim Kosse]

Either a broken firewall or a broken server is interfering with the connection.

Servers and firewalls should reject unknown commands instead of terminating the connection. FTP has specific reply codes for unknown commands.